![]() For example, a device may need to do a temperature conversion or compute a Secure Hash Algorithm (SHA-1) hash. Some devices, however, require additional power delivery at a particular place in the protocol. The DS2482 supports both 1-Wire speeds.ġ-Wire devices normally derive some, or all of their operating energy from the 1-Wire network. All devices support the standard speed overdrive is approximately 10 times faster than standard. Many 1-Wire slave devices can operate at two different communication speeds: standard and overdrive. Used for timing strong pullup operations. Performs the 1-Wire Search Algorithm (see application note 187).ĭelays at least the specified number of milliseconds. Sends to and receives from the 1-Wire network multiple bytes of data. Sends to or receives from the 1-Wire network a single byte of data. Sends to or receives from the 1-Wire network a single bit of data. Sends the 1-Wire reset stimulus and check for the presence pulse of 1-Wire slave devices. These operation names are used throughout the remainder of this document. Table 1 shows the three basic primitives (OWReset, OWWriteBit/OWReadBit, and OWWriteByte/OWReadByte), along with three other useful functions (OWBlock, OWSearch, msDelay) that together make up a core set of basic 1-Wire operations. Similarly there is a byte 1-Wire communication command that is more efficient than doing eight single-bit commands. However, the DS2482 incorporates a search helper function called the 1-Wire triplet, which greatly reduces the communication overhead required for a search. The 1-Wire Search Algorithm can also be constructed using these same three primitives. For example, a byte written to the 1-Wire network is just eight single bit writes. Almost all other 1-Wire operations can be constructed from these three operations. Since the 1-Wire master must start all 1-Wire bit communication, a "read" is technically a "write" of a single bit with the result sampled. ![]() The second function (OWWriteBit) writes a bit from the 1-Wire master to the slaves, and the third function (OWReadBit) reads a bit from the 1-Wire slaves. The first function (OWReset) resets all the 1-Wire slaves on the network, readying them for a command from the 1-Wire master. There are a few basic 1-Wire functions, called primitives, which an application must have to perform any 1-Wire communication session. Simplified illustration of DS2482 function as a bridge for I☬ communication and a 1-Wire network. The DS2482 is available in three configurations, a single-channel 1-Wire master (DS2482-100), a singe channel 1-Wire master with low-power sleep mode (DS2482-101), and an eight-channel 1-Wire master (DS2482-800).įigure 1. This document complements the DS2482 data sheets, but does not replace them. Abstracting the 1-Wire operations in this fashion leads to 1-Wire applications that are independent of the 1-Wire master type. With the exception of programming EPROM-based devices such as the DS250x series, these operations provide a complete foundation to perform all the functions for current and future 1-Wire devices. The I☬ communication for each 1-Wire operation is explained. This document presents an efficient application programming interface (API) implementation of the basic and extended 1-Wire operations using the DS2482. See Figure 1 for a simplified diagram of the DS2482 configuration. The DS2482 I☬ to 1-Wire bridge alleviates the design engineer from implementing the details of 1-Wire timing. The 1-Wire master can be constructed with an IO pin of a microprocessor and manually-generated timing pulses. A 1-Wire network consists of a single master and one or more slave devices.
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